Former Reservist, Alexis, Had History of Mental-Health Issues, Officials Say; Suspect Used Swipe Card to Enter Building

WASHINGTON—New revelations about the Navy contractor who killed 12 people at a secure military installation here have exposed serious shortfalls in security screening and base protection, prompting the White House and Pentagon to order a global review.

President Barack Obama and Defense Secretary Chuck Hagel called for a broad security assessment as the administration and law-enforcement officials tried to determine how a former Navy...